Uploaded songs functionality via android

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I have made an API for upload songs but it is creating problem. When i have upload a song through my android device, it is uploading in my Songs folder but this songs are not playing. Guy's please give me the solution ??
My code is this :
(HowTos)

Basically, I will download new songs to my phone and put them in a playlist with songs that I already had previously. For some reason when I pause the music and lock my phone the songs that I put in recently won't go through the playlist, but the songs I had in the playlist before will still appear and play with no issue.